量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Water window (WW) soft X-rays (wavelength 2.3 to 4.4 nm) are easily absorbed by carbon and are hardly absorbed by water around the living cells. Therefore, X-ray microscopy using WW soft X-ray is expected as a technology for observing nanometer scale structure of living cells. In order to obtain a high spatial resolution image with a soft X-ray microscope, a high intensity soft X-ray source is necessary, and usually high-power lasers of 10 J or more is indispensable. This is a major obstacle to spread and development of soft X-ray microscopes in medical and biological research fields.
Recently, it has been found that when a gold target is irradiated with a commercial Nd:YAG laser (1064 nm, 7 ns, 1 J) under low-pressure nitrogen atmospheres up to 400 Pa, Soft X rays intensity emitted from plasmas increase significantly. Accordingly, a compact and low-cost X-ray microscope can be expected. In this study, in order to generate hot dense plasmas emitting much bright X-ray radiation, picosecond lasers with 10-ps and 500-ps pulse durations were employed. Gas fill circumstance is achieved by introducing nitrogen gas using a mass flow controller. For the soft X-ray measurement, a grazing incidence spectrometer (flat field grating of 2400 grooves / mm) with a toroidal focusing mirror is used. A pinhole camera with an aperture of 0-micron in diameter is also installed to measure two-dimensional X-ray imaging (magnification of 14×). To block the out-of-band radiation, appropriate thin filters are inserted in the pinhole tube.
In this presentation, we will also report the influence on nitrogen gas fill circumstances by using picosecond laser pulses.
会議概要（会議名, 開催地, 会期, 主催者等）
2nd Asia-Pacific Conference on Plasma Physics (AAPPS-DPP2018)
Water window soft X-ray emission from Au plasmas generated with a picosecond laser pulse
